Testimony of W. Seth Carus
Before a Joint Hearing of the
Senate Select Committee on Intelligence
and the
Senate Judiciary Committee
Subcommittee on Technology, Terrorism and Government Information
March 4, 1998

It is an honor to testify before this committee. Biological terrorism, the subject of this hearing, is an important and little understood subject, and I am grateful for this opportunity to present my views on this threat.

Before continuing, let me note that my testimony does not necessarily reflect the views of the National Defense University, where I am a visiting fellow, or the Center for Naval Analyses, my home organization, or the Department of Defense.

Before discussing the dangers to the United States from biological terrorism, let me make a few observations about the nature of bioterrorism.

Biological terrorism

What is biological terrorism? Bioterrorism involves the use of biological agents to further the political objectives of the perpetrators. Biological agents are either pathogens or toxins. Pathogens are microorganisms that cause disease. This includes several hundred organisms. Among the most commonly discussed pathogens considered as biological agents are Bacillus anthracis, the organism that causes anthrax, and Yersinia pestis, the organism that causes plague. In contrast to pathogens, which are living organisms, toxins are poisonous chemicals derived from living organisms. Among the best known toxins are botulinum, which comes from the bacteria Clostridium botulinum, and ricin, which is extracted from the seed of the castor bean plant. While toxins share many characteristics with chemical agents, pathogens are significantly different.

Why would a terrorist use biological agents? A terrorist is likely to employ a biological agent only if it better suits his purposes than alternative weapons. For many purposes, biological agents are more difficult to use and less effective than other weapons. Thus, guns and bombs are probably more than sufficient if the objective is to murder one or even several hundred people. This, partially, explains the apparent lack of interest in bioterrorism.

Resort to biological weapons probably requires one of two motives. First, biological agents could be used to accomplish certain specialized objectives. Thus, a terrorist who wants to incapacitate a large number of people, but not necessarily kill anyone, might rely on biological agents. If the terrorist’s objective is to disrupt agriculture, biological agents could be employed to destroy crops or livestock or contaminate food. Finally, a terrorist seeking to cause disruption that might plausibly be ascribed to natural causes could resort to biological agents.

A second reason for adopting biological agents is to cause mass casualties. It is the potential for causing massive numbers of casualties that creates the most fear. According to the calculations of some experts, biological weapons are pound for pound potentially more lethal than thermonuclear weapons. Thus, the Office of Technology Assessment calculated that 100 kilograms of anthrax spread over Washington could kill from one to three million people under the right conditions. In contrast, a one megaton nuclear warhead would kill from 750,000 to 1.9 million people.**

This threat is not just theoretical. The potential was demonstrated during studies conducted by the United States Army’s Chemical Corps in the 1950s and 1960s, before the United States abandoned its offensive biological warfare program. These tests demonstrated—to the extent possible with the technology then available—that biological agents could be disseminated as an aerosol cloud and infect a large area with potentially lethal infective doses. As this suggests, the most serious threat comes from spreading pathogens in an aerosol cloud. Other routes may pose dangers, but to a significantly lesser extent. Terrorists and criminals have used biological agents to contaminate food and water, but the consequences of such acts will be far more limited than an aerosol dispersion.

This discussion highlights one key, often misunderstood fact. A biological agent is not necessarily a biological weapon. A pathogen growing on a petri dish is unlikely to pose a threat to anyone. What is needed is some means of getting the agent in a form that will infect people. Thus, the key is dissemination. It is possible to spread biological agents by infecting them into people one by one, but that is a method unlikely to meet with much success. Rather, what is needed is a way to infect a large number of people at a time.

Access to biological agents never appears to have been a limiting factor in the misuse of pathogens and toxins, because acquiring biological agents is relatively easy. Despite efforts to restrict the illicit acquisition of biological agents, it is likely that perpetrators will be able to obtain what they want when they want it. If unable to acquire from a legitimate culture collection, such as the American Type Culture Collection, they can steal it from a laboratory. If unable to steal it, a group with the right expertise could even culture the agent from samples obtained in nature. Many biological agents are endemic, and there is nothing to prevent a skilled microbiologist from growing the agent. I will return to this point again later in my testimony when discussing lessons learned from past cases of biological terrorism.

The greatest concern is that a terrorist might attempt to disseminate the biological agents as an aerosol cloud. This delivery method is of concern for several reasons. First, many diseases are most dangerous when contracted in this fashion. Thus, cutaneous anthrax, which is contracted through the skin, has a case fatality rate of 5 to 20 per cent, but antibiotic treatment is highly effective. In contrast, inhalation anthrax is almost always fatal within 3 to 5 days after exposure, and if not detected early there is no effective treatment. Similarly, bubonic plague, generally acquired from the bite of an infected flea, has a case fatality rate of 50 to 60 per cent if untreated, but generally responds to medical treatment. In contrast, pneumonic plague is generally fatal and must be treated earlier.**

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This threat is not just theoretical. The potential was demonstrated during studies conducted by the United States Army’s Chemical Corps in the 1950s and 1960s, before the United States abandoned its offensive biological warfare program. These tests demonstrated—to the extent possible with the technology then available—that biological agents could be disseminated as an aerosol cloud and infect a large area with potentially lethal infective doses. As this suggests, the most serious threat comes from spreading pathogens in an aerosol cloud. Other routes may pose dangers, but to a significantly lesser extent. Terrorists and criminals have used biological agents to contaminate food and water, but the consequences of such acts will be far more limited than an aerosol dispersion.

This discussion highlights one key, often misunderstood fact. A biological agent is not necessarily a biological weapon. A pathogen growing on a petri dish is unlikely to pose a threat to anyone. What is needed is some means of getting the agent in a form that will infect people. Thus, the key is dissemination. It is possible to spread biological agents by infecting them into people one by one, but that is a method unlikely to meet with much success. Rather, what is needed is a way to infect a large number of people at a time.

Access to biological agents never appears to have been a limiting factor in the misuse of pathogens and toxins, because acquiring biological agents is relatively easy. Despite efforts to restrict the illicit acquisition of biological agents, it is likely that perpetrators will be able to obtain what they want when they want it. If unable to acquire from a legitimate culture collection, such as the American Type Culture Collection, they can steal it from a laboratory. If unable to steal it, a group with the right expertise could even culture the agent from samples obtained in nature. Many biological agents are endemic, and there is nothing to prevent a skilled microbiologist from growing the agent. I will return to this point again later in my testimony when discussing lessons learned from past cases of biological terrorism.

The greatest concern is that a terrorist might attempt to disseminate the biological agents as an aerosol cloud. This delivery method is of concern for several reasons. First, many diseases are most dangerous when contracted in this fashion. Thus, cutaneous anthrax, which is contracted through the skin, has a case fatality rate of 5 to 20 per cent, but antibiotic treatment is highly effective. In contrast, inhalation anthrax is almost always fatal within 3 to 5 days after exposure, and if not detected early there is no effective treatment. Similarly, bubonic plague, generally acquired from the bite of an infected flea, has a case fatality rate of 50 to 60 per cent if untreated, but generally responds to medical treatment. In contrast, pneumonic plague is generally fatal and must be treated earlier.**

Second, aerosol transmission makes it possible to spread biological agents over a large area and thus affect a considerable number of people. However, creating a biological cloud poses some real difficulties. Agent stored in a liquid form can be put into a slightly modified commercially-available sprayer, but more than 90 percent of the organisms are likely to die as the liquid is sprayed. Biological agents die or lose virulence once released into the atmosphere. The World Health Organization, for example, estimated that an aerosol cloud containing the organisms that cause Q-fever would decay at a rate of 10 percent per minute. The decay rate for the organism responsible for yellow fever is estimated at 30 percent per minute. However, the rate decay for the agents causing plague and tularemia at only 2 percent per minute, and the decay rate for anthrax is a mere 0.1 percent per minute. This is one of the reasons for the worries about the use of anthrax as a biological agent. All these figures assume that the agents were produced using special stabilizers to protect against adverse environmental conditions**

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Second, aerosol transmission makes it possible to spread biological agents over a large area and thus affect a considerable number of people. However, creating a biological cloud poses some real difficulties. Agent stored in a liquid form can be put into a slightly modified commercially-available sprayer, but more than 90 percent of the organisms are likely to die as the liquid is sprayed. Biological agents die or lose virulence once released into the atmosphere. The World Health Organization, for example, estimated that an aerosol cloud containing the organisms that cause Q-fever would decay at a rate of 10 percent per minute. The decay rate for the organism responsible for yellow fever is estimated at 30 percent per minute. However, the rate decay for the agents causing plague and tularemia at only 2 percent per minute, and the decay rate for anthrax is a mere 0.1 percent per minute. This is one of the reasons for the worries about the use of anthrax as a biological agent. All these figures assume that the agents were produced using special stabilizers to protect against adverse environmental conditions** World Health Organization, Health Aspects of Chemical and Biological Weapons (Geneva: World Health Organization, 1970), p. 94.

There are other potential difficulties in achieving effective dissemination of biological agents, such as the wrong atmospheric conditions.

These comments suggest that aerosolization of pathogens can be extremely difficult. Thus, while it is potentially the most effective way to disseminate agent, the available evidence also suggests that it is significantly more difficult to accomplish than by the alternative methods. This fact plays an important factor in assessing the sources of potential threat from biological agents.

Allow me to make one last comment about bioterrorism. Use of biological agents is different from other terrorist incidents. We are unlikely to know that a biological agent has been released until long after the event. In some cases, depending on the agents employed, we may never know that an outbreak resulted from a terrorist attack. This sharply contrasts with other terrorism incidents. When a terrorist detonates a bomb, we immediately know that something happened, even if we do not know what happened. After a bioterrorism attack, we may only learn about the event as public health officials discover an unusual outbreak days or even weeks after the agent release.

Potential perpetrators

What groups might be motivated to employ biological agents against the United States?

This is a difficult question, since we have little empirical evidence on which to base an answer. Conceptually, however, terrorist groups can be categorized in one of several ways, depending on whether the group is based in the United States or overseas and on whether or not the group receives technical assistance in the use of biological agents from a foreign government.

Traditionally, we distinguished between terrorist groups based in the United States and those based overseas. Domestic groups operated at home, while overseas terrorists attacked American targets around the world. This distinction, however, may be losing some of its value. Domestic groups may have an international perspective. Thus, neo-Nazi organizations promote connections to like-minded groups around the world. Similarly, those responsible for the World Trade Center bombing brought terrorism from the Middle East to downtown New York.

In the context of biological terrorism, however, a more significant distinction may be between those groups that receive support from a state biological warfare program and those without such support. As suggested above, effective employment of biological agents requires specialized expertise that may not be readily available to most terrorist groups. As a result, it is my belief that the greatest concern comes from the possibility that terrorists might be provided with expertise from a state biological warfare program. Yet, one must not discount the possibility of a terrorist group, or even a highly skilled individual, developing the requisite expertise.

A number of countries with records of supporting terrorist organizations also are believed to have biological weapons programs. The Secretary of State has listed seven countries as state supporters of terrorism: Cuba, Iran, Iraq, Libya, North Korea, Sudan, and Syria. According to published reports issued by the Department of Defense and the Arms Control and Disarmament Agency suggest that five of these countries, Iran, Iraq, Libya, North Korea, and Syria, possess biological warfare programs. Press reports have suggested that some Iraqi scientists may be working in Sudan. Thus, almost all the countries associated with support for international terrorism also support efforts to develop biological weapons.

Unfortunately, relatively little is known about the activities of any of these countries, except for Iraq due to the efforts of UNSCOM. What little is known suggests that the sophistication of these programs varies considerably. Based on publicly available information, it appears the most sophisticated of these programs is almost certainly Iraq’s. Less is known about North Korea’s activities, but it has been conducting research in the area of biological warfare for more than thirty years and probably has capabilities equal to or greater than Iraq’s. Iran probably comes next in competence, followed by Syria and Libya. If it exists, Sudan’s program is probably an off-shoot of the Iraqi program.

Under what circumstances might a hostile state be willing to provide biological warfare expertise to a terrorist group? There is no evidence that such an exchange has ever taken place. However, there is a growing recognition in the national security community that hostile states, intent on countering the power of the United States, might be inclined to adopt asymmetric responses. One possible response is an ability to threaten the American homeland with biological terrorism.

The current confrontation with Iraq highlights the potential significance of state support for biological terrorism. Based on the investigations conducted by UNSCOM, we know that the Iraqis have a sophisticated biological weapons program. We also know that Iraq has supported terrorist activities in the past, although not always with great success. In the event of a conflict with Iraq, it is certainly possible that the Iraqis would chose to retaliate by using biological weapons against U.S. military forces in the Gulf region, or against U.S. allies in the area, or even against the people of the United States.
Terrorist interest in biological weapons

It is sometimes argued that terrorists have little or no interest in biological weapons. Some argue that there are moral inhibitions against the use of biological weapons, either because the terrorists subscribe to the moral tenets or because their supporters do. Others contend that biological agents are too dangerous for terrorists to use. This is based on the argument, as articulated in 1985 by terrorism expert Bryan Jenkins, “Terrorists want a lot of people watching, not a lot of people dead. Most terrorists adhere to the principle of ‘minimum force necessary’ to achieve their tactical objectives.” Similarly, the FBI has publicly suggested that they have little evidence of a credible bioterrorism threat against the United States. This is consistent with my own research using publicly available material.

It is true that terrorists have shown remarkably little interest in biological agents, but this is not the same as demonstrating no interest. Publicly available information makes it difficult to assess the extent to which terrorist groups are attracted to biological weapons. During the past thirty years, press accounts have identified more than thirty terrorist groups that are alleged to have had some interest in biological agents. Generally, it is impossible to prove such claims, experience suggests that the great majority of the claims are false or exaggerated. Fortunately, in most cases it appears that the terrorists had no serious intention to employ the biological agents.

Unfortunately, in some cases the evidence clearly demonstrates that the terrorists had a serious interest in biological weapons. Disturbingly, several of the groups expressing an interest in biological warfare are located in the United States. For example, a member of the Aryan Republican Army, a right wing group responsible for a number of bank robberies, claimed on a publicly released video tape that his group had the ability to employ biological agents. Similarly, the Minnesota Patriot’s Council produced ricin toxin, possibly to assassinate law enforcement government officials.

Terrorists use of biological agents.

It is often asserted, falsely as it happens, that there has never been an incident of biological terrorism. The reality is that on several occasions terrorists have used biological agents. Let me describe the two most significant cases in which terrorists used biological agents.

Rajneeshees

The first incident took place in the United States, and involved a religious cult that originated in India. The Rajneeshees, led by their guru, the Bhagwan Shree Rajneesh, moved to the United States in 1981 and established a commune in rural Oregon. After coming into conflict with the local inhabitants, in 1984 the Rajneeshees concocted a plot to seize political control of the county where they resided. To accomplish this objective, the Rajneeshees decided that they would expand their voter rolls by importing homeless people and that they would decrease the number of hostile voters by spreading diseases that would make the local inhabitants too sick to vote. To accomplish this, the Rajneeshees spread Salmonella typhimurium, which causes food poisoning, on the salad bars of the small town of The Dalles. Fortunately, this strain of salmonella is rarely fatal, although they did consider using Salmonella typhi, the agent that causes typhoid fever. The case fatality rate for typhoid can reach 10 per cent. The Rajneeshees also attempted to infect the town’s water supply. While the plot failed, the Centers for Disease Control and Prevention determined that 751 people became ill. More than 40 had to be hospitalized.

Aum Shinrikyo

The second incident also involved a cult, the Japanese group known as Aum Shinrikyo. This is the group that gained notoriety on March 20, 1995 when it released the nerve agent sarin in the Tokyo subway. Like the Rajneeshee group, Aum Shinrikyo is a religious group founded by a charismatic leader, Shoko Asahara. Founded in 1984, Aum is heavily influenced by Indian mysticism. The group became extremely successful, and gained thousands of adherents and gained access to substantial financial resources. By the late 1980s, Asahara developed an intense hostility towards Japanese society and towards the United States. As a result, he initiated development of weapons programs intended for use against mainstream Japan. Aum adopted a range of programs, including a substantial program to develop chemical weapons. Of significance for today’s hearings, it is reported that Aum also developed an extensive biological weapons program.

The Japanese government has released virtually no official information about Aum’s biological program, so what we know is limited to what investigative journalists have written. My account today is based on the book written by David Kaplan and Andrew Marshall, The Cult at the End of the World. According to their research, the Aum built two substantial biological research facilities, one located at the cult’s Mount Fuji base and the other on the eighth story of an office building owned by the cult in eastern Tokyo. The Aum was attempting to produce biological agents as early as 1990, even before they started their program to manufacture chemical agents. According to Kaplan and Marshall, the Aum investigated a variety of agents, including anthrax, botulinum toxin, Q-fever, and possibly the Ebola virus. It appears that in 1992 the Aum sent a large team of scientists and health care providers to Zaire to obtain Ebola.

On at least four occasions, the Aum reportedly attempted to employ their biological agents.
In April 1990, the Aum Shinrikyo outfitted an automobile to disseminate botulinum toxin through the engine’s exhaust. The car was then driven around the building where Japan’s parliament, the Diet, meets.
In early June 1993, the cult attempted to disrupt the planned wedding of Prince Naruhito, Japan’s Crown Prince, by spreading botulinum toxin in downtown Tokyo using the same specially-equipped automobile.
In late June 1993, the cult attempted to spread anthrax in Tokyo using a sprayer system on the roof of an Aum-owned building in east Tokyo. The anthrax was disseminated for four days.

On March 15, 1995, the Aum planted three briefcases designed to release botulinum toxin in the Tokyo subway. Apparently, the individual responsible for filling the botulinum toxin had qualms about the planned attack and substituted a non-toxic substance. It was the failure of this attack that led the cult to use sarin in its March 20, 1995 subway attack.

Fortunately, all of these attacks appear to have failed. Unfortunately, we do not know the reason for the failures. It is possible that the Aum failed to culture a dangerous strain of botulinum, and hence never produced any toxin. Similarly, it is possible that the Aum made mistakes in their efforts to produce anthrax for the 1993 attack. However, the Aum apparently did produce virulent pathogens, since they reportedly also laced the food served at some banquets with biological agents to determine the effectiveness of their biological agents.

Lessons from history

What can we learn from past instances of bioterrorism?

While it is dangerous to draw too many firm conclusions from a small sample, there are some insights that can be gleaned from a survey of these past incidents.

First, it is relatively easy to gain access to biological agents. Perpetrators have managed to obtain biological agents in many ways. The Rajneeshees obtained their agent from a medical supply house. Significantly, they could do the same today under current regulations, since the organism they used is not on the control list and in any case they had a state certified clinical laboratory with a legitimate reason to acquire such agents. We do not know where Aum Shinrikyo obtained its biological agents, although there are suspicions that it acquired the agents from legitimate suppliers. Other perpetrators have acquired biological agents by stealing them from laboratories or by making it themselves. Thus, the Minnesota Militia, which produced a quantity of ricin toxin, made it themselves from a recipe obtained from a book. There are numerous readily available books that purport to describe techniques for extracting ricin from caster beans.

Second, using biological agents in a simple way is not difficult, but aerosolization is much harder than often asserted. The Aum Shinrikyo devoted substantial resources to their biological warfare program, but never managed to use it effectively. We do not know what they did wrong, but we do know that they had highly skilled scientists and technicians working in well equipped laboratories. This suggests that employing biological agents, especially through the aerosol route, is far more difficult than often claimed.

Third, hiding biological weapons programs is easy to accomplish. The efforts of the Rajneeshees to develop biological agents were never detected. Indeed, it took more than a year to determine that the outbreak they caused was due to intentional contamination. An intensive public health investigation of the outbreak failed to determine the cause of the outbreak. In fact, the State of Oregon issued a report claiming that unsanitary practices by restaurant workers caused the outbreak and dismissing allegations that intentional contamination was a factor. It was only a year later that law enforcement officials developed credible evidence that intentional contamination was responsible for the outbreak.

Similarly, there is no evidence that Japanese authorities were aware of the Aum Shinrikyo’s activities. Only after the sarin attack on the Tokyo subway did law enforcement officials learn of the biological warfare program and hear about the allegations that Aum actually attempted to use biological agents on Tokyo. Despite the virulent anti-American ideology of Aum, it also appears that U.S. intelligence agencies were completely in the dark about Aum’s activities.
Conclusions

In conclusion, I would like to advance several propositions about the nature of the threat from biological terrorism.

First, while it is unlikely that we will witness a significant bioterrorism attack, the consequences of such an event are sufficiently great to justify concerted efforts to develop an effective government response. Even if there is little evidence to suggest substantial interest in biological terrorism, the dangers from even a single well executed attack are so substantial that the federal, state, and local authorities need to have prepared and trained response capabilities.

Second, although there is little evidence to suggest that terrorists and other perpetrators have the skills needed to effectively employ biological agents to inflict mass casualties, we should assume that efforts will be made to acquire such capabilities. Without assistance from a state biological weapons program, domestic groups will need to go through a learning process. This may provide opportunities for the law enforcement community to catch the perpetrators before they develop all the necessary skills. For this reason, it is encouraging to see the alert response of the FBI in the recent Las Vegas incident. While it soon became clear that the alleged perpetrators posed no real threat, the vigor of the response is a sharp contrast to lack of interest law enforcement officials showed to such cases in the recent past. More disturbing is the possibility that domestic or foreign groups might obtain assistance from a state weapons program. Especially alarming is the possibility that some group might exploit the expertise of scientists and technicians from the former Soviet biological warfare program. While active vigilance might prevent domestic groups from developing their own capabilities, it will not prevent them from acquiring skills and supplies from overseas.

Second, we cannot rely on advance warning of an impending biological attack. Experience suggests that it is unlikely that we will receive the intelligence information about the plans and intentions of groups intent on using biological agents. Moreover, it is even possible that it will not be possible to determine that intentional contamination was the cause of an outbreak even after it happens. While steps need to be taken to enhance the prospects of detecting perpetrators involved with biological agents before they use them, we should not assume success. Rather, we need to ensure that we have taken appropriate steps to manage the consequences of a biological terrorism attack.

Third, responding to the challenge of bioterrorism poses a difficult challenge for those responsible for domestic security. The threat cannot be handled merely by law enforcement and intelligence organizations. Those responsible for consequence management need to be an integral part of the process, including diverse groups drawn from FEMA, the Department of Health and Human Services, the Veteran’s Administration, and the Department of Defense. Because of the nature of bioterrorism, the public health infrastructure becomes critically important, both to detect an outbreak and to deal with the consequences. Accordingly, we need to ensure that federal, state, and local disease surveillance systems are operating effectively, and that we improve the capabilities of federal, state, and local public health laboratories to support responders.

We have made considerable progress during the past two years in developing responses to the threat of nuclear, biological, and chemical terrorism. However, we are still learning about the complexities of the problem, and there is much more to be done. For that reason, I hope that your committees will continue to remain engaged in efforts to enhance capabilities to respond to the threat of biological terrorism.